respond to some student suggestions and comply with funder policy

NEH requires that funded projects include a disclaimer along with their logo on grant products. I've added the disclaimer and corresponding style.

Students at UTexas expressed some confusion about navigating from the splash page into the site and about finding the help. They also expressed a desire to be able to go straight to the login form from the splash page. Accordingly I've added some link elements in the header top right mimicing what plone does there (so the header here will cohere visually with the main header on the site).